#include <iostream>
#include <string>
using namespace std;

class Solution {
  public:
    bool isNumber(string s) {
        int i = 0;
        while (i < s.size() and s[i] == ' ') ++i;
        if (s[i] == '-' or s[i] == '+') ++i;
        bool have_e = false, have_dot = false, have_digit = false;
        for (; i < s.size(); ++i) {
            if (s[i] == ' ') {
                for (; i < s.size(); ++i)
                    if (s[i] != ' ') return false;
                break;
            }
            if (s[i] <= '9' and s[i] >= '0') {
                have_digit = true;
            } else if (s[i] == 'e' or s[i] == 'E') {
                if (have_e or (not have_digit)) return false;
                have_e = true;
                if (s[i + 1] == '+' or s[i + 1] == '-') ++i;
                have_digit = false;
            } else if (s[i] == '.') {
                if (have_dot or have_e) return false;
                have_dot = true;
            } else {
                return false;
            }
        }
        return have_digit;
    }
};

int main() { std::cout << static_cast<int>('0') << ", " << static_cast<int>('9') << std::endl; }
